If you share your house with several children (as I do) it’s quite common for one kid to grab another kid’s toothbrush, creating a pathway for infection. I decided that this problem was real when my oldest boy got a cold sore on his lip, and my youngest daughter mysteriously acquired one of her own a week later.
The human mouth is well known to be crawling with viruses and bacteria, and a toothbrush naturally picks up its share, along with some saliva to form an excellent culture medium. A toothbrush sitting innocently in the bathroom may be one of the least hygienic items in your home.
Several sterilizers are available, but this one seems the best to me, using ultraviolet light instead of steam. It’s also useful if you have a guest who didn’t plan to stay overnight and came without his own toothbrush. He won’t catch anything from you, and you won’t catch anything from him (at least, not by him brushing his teeth).